Method of bluing sheets and plates.



' A. RIDD. v

METHOD OF BLUING SHEETS AND PLATES.

APPLICATION FILED MAR. 27. #916.

Patented July 25, 1916.

2 SHEETS-SHEET I WITNESSES AMBROSE RIDD, OF FARRELL, PENNSYLVANIA.

METHOD OF BLUING SI lIEETS AND PLATES.

Specification of I .ters Patent.

Patented July 25, 1216.

Application filed March 27, 1916. Serial No. 86,927.

of blued sheets and plates of rolled ferrous metal. 7

One object of the invention is to provide a a novel method of bluing such rolledsheets and plates wherein individual sheets or plates are uniformly heated within a suit able furnace to the desired temperature and the individually heated sheets or plates are gradually withdrawn from the furnace and progressively cooled by exposure to the atmosphere in oxidizing the surfaces of the plates to an equable blue color.

Another object of this invention is to provide an improved method of bluing rolled metal sheets and plates whereby overheating of the edges of the sheets is avoided and prevented and the necessity of heating the sheets or plates in bulk or packs is overcome and made unnecessary, and wherein the sheets or plates are heated individually and in a substantially continuous manner and the desired uniform coloron the surfaces of the sheets is obtained.

Referring now to the drawings forming part of this specification, Figure 1 is a longitudinal, sectional side elevation showing a furnace of the Inufile type made in accordance with my invention and adapted for use in carrying out the improved method forming part of this invention. Fig. 2 1s a sectional end elevation of the furnace shown in Fig. 1, the section being taken on the line II-II of Fig. 1. Fig. 3 is a sectional plan of a portion of the furnace shown in Figs. 1 and 2, showing the staggered arrangement of the supporting rollers as arranged in accordance with my invention. I

In the accompanying drawings, the numeral 2 designates the heating or combustion chamber of a gas fired furnace having.

side walls 3, 3, and end walls l, 4, with an arched roof 5 carried by the side walls.

The furnace is provided with a stack 2 of any-of *he usual known constructions. P0- sitioned within the furnace chamber 2 is a mufile 6 formed of metal or of tiles, bricks, or such other refractory material as is found necessary. or desirable. open ends forming an inlet opening 7 and outlet 0 ening 8, connecting the interior of the mu e with the exterior of the furnace, the ends of themufile being built into and supported by the end wallspf the furnace. Suitable transverse supports .(not shown) may be provided at intervals in the length of the furnace chamber 2 to sustain the The mufie 6 has muffle when its length makes such supports sage to regulate and control the temperature to which the middle of the heating chamber 2 and muflie 6 is'heated.

Located in the sidewalls 3 of the furnace at the bottom of the chamber 2 is a series of openings 13 for the gas burners 13 which are similar to the burners 12 and. have gas pipes 14 and air pipes 15,are valves 16 and gas valves 16 being provided on the burner pipes 12 and 13 to control the air and gas supply in regulating the heating of the furnace chamber and muflle to obtain the desired uniform temperature within the muflie or bluing chamber 6.

Positioned within the muflle 6 on the bottom thereof is a series of transverse supports 17 for the series of idler rollers 18.

in the mufiie andv on which the sheets or plates 19 are sup-ported when being heated and in passing into and through the furnace muffle 6. The rollers 18 are arranged in two converging rows, the pairs of rollers being at av distance apart which increases from one end to the other of the furnace, so that inplan the rollers 18 are in staggered relation, this construction causing the sheetsor plates 19 to be supported upon changing and successively different portions of the lower surface of the sheets and plates and thereby assisting in equa'blyheating the sheets and plates to the desired temperature. Extending lengthwise within the muflie 6 adjacent to each vertical side wall 20 thereof is a series of cooling tubes 21 through which a supply of cold or cool air is passed, the tubes 21 being located at the sides of the muffle 6- to prevent overheating of the mufiie at the side walls thereof, as would otherwise occur and in this Way assist in securing the desired uniform temperature within the mufiie 6. Fastened so as to be adjustable on the supports 17 for the idler rollers 18 within the muflie chamber are vertically extending metal shields 22, 22, these shields being adjustable sidewise within the muflie to suit the particular width of the sheets or plates being heated. The upper edge 23 of the shields'22 is inclined upwardly and inwardly tooverlap the edges of the sheets or plates ,being heated, the shields being employed to protect and prevent overheating of the longitudinal edgesof the sheets and plates. I

A pair of pinch rollers 24, 24, at least one of which is positively driven, are provided atthe inlet end of the muffle which are arranged to be driven .at variable speeds to suit the varying thicknesses and sizes of sheets and plates, these rollers being employed to feed the plates 19 into the furnace at the required speed. 'A similar pair of positively actuated pinch rollers 25, 25, at the exit end of the mufile 2 affords means for feeding the heated sheets forwardly out of the furnace into the atmosphere.

In carrying out my improved method with the apparatus which has been described the gas burners 12 and 13 are first carefully regulated to uniformly heat the combustion chamber 2 and the interior of the muflie 6, and cold air is caused to pass through the pipes 21 to maintain the sides of the muflie at the desired temperature. The sheets and plates, after being cleaned by pickling or cold rolling, or by both pickling and. cold rolling, to remove all scale and provide the materials with clean metallic surfaces, are moved singly by the pinch rollers 24, 24, into the inlet end of the muflie where each plate is allowed to remain until evenly heated throughout to a black-red color, a-tempera ture corresponding to between 750 degrees and 1000 degrees Fahrenheit. Upon becoming heated the sheet or plate is gradually moved through the mufile by the pinch rollers 25, the furnace preferably being of such length as will enable the pinch rollers 25 to engage with the front end of the plate before the rear end is clear of the feed-in pinch rollers 24. p

The front end of the individual sheet or plate passes from the interior of the muflie 8.

into the atmosphere, and as the successively different portions of the heated sheet or plate become exposed to the atmosphere the ,cooling effect of the, air will oxidize the heated sheetsand plates to a uniform blue color, and the plates, (and successively ex osed portions of the individual plates) ing equally heated to the same temperature as they emerge from the muffle, variations in a or passed through the cooling tubes 21-within the furnace lmuflie is regulated from time to time so as to heat the interior of the muflie equably. The operator, knowing the speed at which the plates can be fed into and through the furnace in order to become I equally heated, will cause the pinch rollers 24 and 25 to move the plates at the desired" rate of speed.

The above described operations are then carried out on. each individual sheet and plate, each sheet'or plate being treated as a separate unit.

The advantages of my invention will be appreciated by those skilled in the art. 'By heating the individual sheets and plates to a uniform temperature within a muflie and progressively exposing the successively heated portions of the sheets and plates to the oxidizing influence of the atmosphere,

each sheet and plate is blued to the desired uniform color, and the necessity of heating the sheets and plates in packs and then removing and exposing. the heated plates singly to the oxidizing atmosphere by removing the sheets and plates singly from the heated pack, is avoided and overcome.

Modifications in the construction and arrangement of the parts of the apparatus used in carrying out this invention may be made without departing from my invention as defined in the appended claims.

I claim 1. In the manufacture of blued sheets and plates the steps consisting in heating individual sheets or plates equably within a muffle furnace to a black-red color, then withdrawingthe uniformly heated sheet or plate from the muflie into the atmosphere, protecting the edges of the sheet or plate in heating and gradually exposing the heated sheet or plate to the action of the atmosphere in the withdrawal thereof to thereby fix the color of the blued sheet or plate.

2. In the manufacture of blued sheets and withdrawal thereof to thereby fix the color plates the steps consisting in heating indiof the blued sheet or plate. 10 vidual sheets or plates equably within a In testimony whereof I have hereunto set mufi'ie furnace to a black-red color, then my hand.

withdrawing the e uably heated sheet or AMBROSE RIDD. plate from the mu e into theatmosphere, Witnesses: and gradually exposingthe heated sheet or CHESTER A. LEWIS,

plate to the action of the atmosphere in the MARGARET DAVIS. 

